Incorporate ComputedStyle::hasTransform when diffing transform styles.

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 1009 matching lines @@
 }
 
 void ComputedStyle::updatePropertySpecificDifferences(
     const ComputedStyle& other,
     StyleDifference& diff) const {
   if (m_box->zIndex() != other.m_box->zIndex() ||
       isStackingContext() != other.isStackingContext())
     diff.setZIndexChanged();
 
   if (m_rareNonInheritedData.get() != other.m_rareNonInheritedData.get()) {
-    if (!transformDataEquivalent(other) ||
+    // It's possible for the old and new style transform data to be equivalent
+    // while hasTransform() differs, as it checks a number of conditions aside
+    // from just the matrix, including but not limited to animation state.
+    if (hasTransform() != other.hasTransform() ||
+        !transformDataEquivalent(other) ||
         m_rareNonInheritedData->m_perspective !=
             other.m_rareNonInheritedData->m_perspective ||
         m_rareNonInheritedData->m_perspectiveOrigin !=
             other.m_rareNonInheritedData->m_perspectiveOrigin)
       diff.setTransformChanged();
 
     if (m_rareNonInheritedData->opacity !=
         other.m_rareNonInheritedData->opacity)
       diff.setOpacityChanged();
 
@@ skipping 1457 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 }  // namespace blink